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minio/pkg/madmin/encrypt.go

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4.4 KiB

/*
* MinIO Cloud Storage, (C) 2018 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package madmin
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"io"
"io/ioutil"
"github.com/secure-io/sio-go"
"golang.org/x/crypto/argon2"
"golang.org/x/crypto/chacha20poly1305"
"golang.org/x/sys/cpu"
)
// EncryptData encrypts the data with an unique key
// derived from password using the Argon2id PBKDF.
//
// The returned ciphertext data consists of:
// salt | AEAD ID | nonce | encrypted data
// 32 1 8 ~ len(data)
func EncryptData(password string, data []byte) ([]byte, error) {
salt := make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, salt); err != nil {
return nil, err
}
// Derive an unique 256 bit key from the password and the random salt.
key := argon2.IDKey([]byte(password), salt, 1, 64*1024, 4, 32)
// Create a new AEAD instance - either AES-GCM if the CPU provides
// an AES hardware implementation or ChaCha20-Poly1305 otherwise.
id, cipher, err := newAEAD(key)
if err != nil {
return nil, err
}
stream := sio.NewStream(cipher, sio.BufSize)
nonce := make([]byte, stream.NonceSize())
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
// ciphertext = salt || AEAD ID | nonce | encrypted data
cLen := int64(len(salt)+1+len(nonce)+len(data)) + stream.Overhead(int64(len(data)))
ciphertext := bytes.NewBuffer(make([]byte, 0, cLen)) // pre-alloc correct length
// Prefix the ciphertext with salt, AEAD ID and nonce
ciphertext.Write(salt)
ciphertext.WriteByte(id)
ciphertext.Write(nonce)
w := stream.EncryptWriter(ciphertext, nonce, nil)
if _, err = w.Write(data); err != nil {
return nil, err
}
if err = w.Close(); err != nil {
return nil, err
}
return ciphertext.Bytes(), nil
}
// DecryptData decrypts the data with the key derived
// from the salt (part of data) and the password using
// the PBKDF used in EncryptData. DecryptData returns
// the decrypted plaintext on success.
//
// The data must be a valid ciphertext produced by
// EncryptData. Otherwise, the decryption will fail.
func DecryptData(password string, data io.Reader) ([]byte, error) {
var (
salt [32]byte
id [1]byte
nonce [8]byte // This depends on the AEAD but both used ciphers have the same nonce length.
)
if _, err := io.ReadFull(data, salt[:]); err != nil {
return nil, err
}
if _, err := io.ReadFull(data, id[:]); err != nil {
return nil, err
}
if _, err := io.ReadFull(data, nonce[:]); err != nil {
return nil, err
}
key := argon2.IDKey([]byte(password), salt[:], 1, 64*1024, 4, 32)
cipher, err := parseAEAD(id[0], key)
if err != nil {
return nil, err
}
stream := sio.NewStream(cipher, sio.BufSize)
return ioutil.ReadAll(stream.DecryptReader(data, nonce[:], nil))
}
const (
aesGcm = 0x00
c20p1305 = 0x01
)
// newAEAD creates a new AEAD instance from the given key.
// If the CPU provides an AES hardware implementation it
// returns an AES-GCM instance. Otherwise it returns a
// ChaCha20-Poly1305 instance.
//
// newAEAD also returns a byte as algorithm ID indicating
// which AEAD scheme it has selected.
func newAEAD(key []byte) (byte, cipher.AEAD, error) {
if (cpu.X86.HasAES && cpu.X86.HasPCLMULQDQ) || cpu.S390X.HasAES || cpu.PPC64.IsPOWER8 || cpu.ARM64.HasAES {
block, err := aes.NewCipher(key)
if err != nil {
return 0, nil, err
}
c, err := cipher.NewGCM(block)
return aesGcm, c, err
}
c, err := chacha20poly1305.New(key)
return c20p1305, c, err
}
// parseAEAD creates a new AEAD instance from the id and key.
// The id must be either 0 (AES-GCM) or 1 (ChaCha20-Poly1305).
func parseAEAD(id byte, key []byte) (cipher.AEAD, error) {
switch id {
case aesGcm:
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
return cipher.NewGCM(block)
case c20p1305:
return chacha20poly1305.New(key)
default:
return nil, errors.New("madmin: invalid AEAD algorithm ID")
}
}